Inactivation of Staphylococcus epidermidis in a Cotton Gauze with Supercritical CO2 Modified with Essential Oils

The bacterium Staphylococcus epidermidis is the main cause of most infections related to medical devices and prosthesis. However, current disinfection methods are not satisfactory; a new one is proposed here. S. epidermidis was spiked in a cotton gauze and then treated with supercritical CO2 mixed with essential oils, such as lemon, cinnamon, oregano, clove, and peppermint, and isolated thymol. The operation took 30 min at 10.0 MPa and 40 °C. Concentrations of 1000, 500, and 200 ppm of the essential oils were used. These additives, which have antimicrobial power by themselves, improved the inactivation with supercritical CO2. The peppermint essential oil was the most effective. The presence of water from 200 ppm also improved the disinfection. Thus, S. epidermidis total inactivation was achieved with the supercritical CO2 containing 200 ppm of peppermint essential oil and 200 ppm of water. An evaluation of the gauze before and after disinfection was realized by DSC, FTIR, and SEM. At the optimal conditions, there were no significant physical or chemical changes. Furthermore, no essential oil residuals were found. This disinfection method could be established in the healthcare field as an alternative to toxic liquid chemicals.